I have a JDM ZC 1.6L engine I just put in my 1994 Honda Civic LX. Everything is working all right. No loss of power, performance or anything. However, I can hear this dull knocking noise when the engine is running. I am pretty sure it is not the timing or the gas I am running (timing set to
16 DB TDC and 92 octane). I'd say it sounds like piston slap but the again I never heard what piston slap sounds like. By the way, the sound is always there, whether the car is cold or at normal temperature. I did a compression test and here are the results (from cylinder 1 to 4): 150psi, 184psi,182psi,184psi I did some more testing on cylinder 1 and the pressure build up quickily during the first two strokes but at the third stroke the pressure maxed out and further strokes only increased the pressure buildup marginally. After this I added three squirts of oils through the spark plug hole and retested, and the pressure came out to be the same. No increase. I thought I might have been hearing piston slap at cylinder 1, but I guess this means it is probably not the piston rings? Could the noise come from one the accessories? Could it be the valve or the camshaft? Thanks in advance for any help,- JR